This invention relates to a process for continuously producing acrylamide or methacrylamide from acrylonitrile or methacrylonitrile by use of microorganisms.
A process for producing acrylamide or methacrylamide (hereinafter both referred to simply as "(meth)acrylamide") by reacting acrylonitrile or methacrylonitrile (hereinafter both referred to simply as "(meth)acrylonitrile") with water in the presence of a copper-based catalyst has hitherto been known, but this process has disadvantages in that the preparation of the copper-based catalyst is complex, the reproduction of the catalyst is difficult, and the separation and purification of the (meth)acrylamide formed is complicated. It has therefore been desired to develop improved processes which can be used advantageously from a commercial standpoint.
Recently, U.S. Pat. No. 4,001,081 has disclosed a process for the biological production of (meth)acrylamide from (meth)acrylonitrile using microorganisms belonging to the genera Bacillus, Bacteridium in the sense of Prevot, Micrococcus and Brevibacterium in the sense of Bergey.
Another process proposed for the production of (meth)acrylamide from (meth)acrylonitrile using microorganisms belonging to the genera Corinebacterium and Nocardia is described in Japanese Patent Application (OPI) No. 129190/79 (the term "OPI"0 as used herein refers to a "published unexamined Japanese patent application").
The microorganisms disclosed in both U.S. Pat. No. 4,001,081 and Japanese Patent Application (OPI) No. 129190/79 exhibit high initial activity for the hydration reaction. However, because of their quick reduction in activity under ordinary reaction conditions, their useful lives are short. Therefore such microorganisms have not been able to effect a sufficient increase in the accumulated concentration of (meth)acrylamide, and the repeated use of the microorganisms has been almost impossible. Furthermore, since the microorganisms are of very small size, if they are used in their natural state, it is difficult to remove them from the aqueous solution of (meth)acrylamide formed and the aqueous solution of (meth)acrylamide separated from the microorganisms is discolored, causing obvious problems when used in the production of polymers.